Stator adjusting means for axial flow compressors or the like



Dec. 5, 1967 R J, CORSMElER 3,355,288

STATOR ADJUSTING MEANS FOR AXIAL FLOW COMPRESSORS OR THE LIKE Filed April 7, 1965 'llI/l//lli l Y I l United States Patent ABSTRACT OF THE DISCLOSURE An axial flow compressor or the like includes axially spaced-apart rows of stator vanes, each vane being disposed radially and being mounted for rotation about its radial axis. Simple and economic means are provided for accurately and simultaneously adjusting the angular positions of the stator vanes.

The present invention relates to improvements in axial flow compressors and more particularly to improved means rfor adjusting the relative angular disposition of stator vanes employed in such compressors or the like.

Axial flow compressors, as used in gas turbine engines,

generally incorporate a plurality of stages, each comprising a fixed row of radially disposed, angularly spaced stators and a row of rotating radially disposed and angularly spaced turbine blades. In order that maximum operating efficiency be obtained from the compressor, it is desirable that the stators be pivotally adjustable about a radial axis of the compressor in order that the angle of attack of the air or other gas may be properly maintained for maximum efficiency at various rates of gas flow and velocity.

Recent developments in compressor design have resulted in the successive stages of the compressor being very closely spaced in an axial sense. This has presented a serious problem in being able to obtain the necessary or desired pivotal adjustment of the individual stator yblades of each stage. It has been an accepted practice to attach a lever to each stator on the exterior of the compressor housing. An actuator ring for each stage will swing these levers the necessary distance to impart the pivotal adjustment required for each of the stators in a given stage. The close axial spacing above referred to makes it difficult, if not impractical, to obtain sufiicient accuracy in the pivotal adjustment of the stators for maximum efficiency and reliable operation.

Accordingly, it is an object of the present invention to provide simple and economical means for accurately and simultaneously adjusting the relative angular position of the stator vanes of a given stage in an axial flow cornpressor or the like, and particularly to provide such improved means which give a high degree of accuracy where the stages of the compressor are closely spaced in an axial direction.

In obtaining the broader aspects of the above ends, lever arms, disposed exteriorly of the compressor housing, are provided on each of the stators. Each of the lever arms is received by a clevis pin which is pivotally mounted in an actuator ring. Each actuator ring is guided for oscillating movement in a fixed plane disposed normal to the axis of the compressor casing. This arrangement enables a high degree of accuracy in obtaining a desired angular position of each of the stators relative to its radial axis.

This structural arrangement further enables the use of levers of a maximum length which overlies the structure of an adjacent stage of stators so as to provide the desired accuracy of adjustment where the stator stages are closely spaced in an axial sense.

The above and other related -objects and features of ice the invention will be apparent from a reading of the following description of the disclosure found in the accompanying drawing, and the novelty thereof pointed out in the appended claims.

In the drawing:

FIG. l is a fragmentary longitudinal section of an axial flow compressor embodying the present invention:

FIG. 2 is a plan view of a portion of the compressor seen in FIG. 1:

FIG. 3 is a perspective view illustrating a modified embodiment of the invention:

FIG. 4 is a section taken on line IV-IV in either of FIGS. 2 or 3: and

FIG. 5 is a longitudinal section of an axial flow compressor `illustrating a modified embodiment of the invention.

FIG. l fragmentarily illustrates an axial ow cornpressor comprising an outer casing 10 and inner frame members 12. Seven adjustable compressor stages a, b, c, d, e, f, and g are shown, though more or less might be used. Each stage comprises a row of stator blades 14 and a row of rotating compressor blades 16. The compressor blades 16 are mounted on a rotor 18 and function in conventional fashion insofar as the present invention is concerned. In the following description, the structure of the various compressor stages is identified by like reference charatcers for ease of understanding and the differences in structure between stages is pointed out where appropriate.

The stators 14 are each mounted by stud shafts 20, 22 journaled in the casing 10 and frame 12 respectively for pivotal movement about an axis extending radially from the center of rotation of the rotor 18, i.e., the axis of the compressor which in turn is the axis of the casing 10. The stators 14 of each stage are preferably equi-angularly spaced from each other in a plane which is generally normal to the casing axis.

A lever arm 24 is secured to the outer end of each stud 20 by a nut 26 and accurately positioned in predetermined relation relative to the contour of the stator 14 to which it is connected. The free end of each lever 24 extends into a slot 28 (FIGS. 2 and 4) formed in a clevis pin 30 associated therewith. An actuator ring 32 pivotally receives all of the clevislpins 30 for a given stage of the compressor.

The actuator ring 32 comprises an annular ring 34 disposed in a radial plane and has three concentric, spaced circular fianges projecting therefrom which are respectively identified by reference characters 36, 38, and 40. The flanges 38 and 40 have holes formed therein which pivotally journal the pins 30. The flange 36 is shorter than the flange 3S and has semicircular openings therein providing access to the holes in the flanges 38, 40. The pins 30 are each slotted to receive snap rings 42 employed in retaining the pins on the actuator ring 32. A second groove indicated at 44 is formed in each of the pins 30 to facilitate its removal. Thus the snap ring 42 may be spread by the use of appropriate pliers and a screw driver or a persons fingernail may be employed to withdraw the pin 30 from the actuating ring.

Each of the actuator rings 32 is mounted for pivotal movement in a plane normal to the axis of the compressor. The means for so mounting the actuator rings may take dierent forms but advantageously each of the actuator rings is provided with a circumferential slot 46, formed in an inwardly projecting flange 47, which guidingly receives a series of angularly spaced studs 48 threaded into the casing 10. It will, of course, be appreciated that the rings 34 may be formed of two halves and joined together to facilitate assembly.

One of the advantages of the present stator adjusting means is that the structure for adjusting one stage may overlie the structure of an adjacent stage and thus provide the levers 24 with a sufficient length for obtaining a high degree of accuracy in the angular positioning of all the stators. The spacing between compressor stages a and b is such that the ange 47 of the actuator ring 32 is most conveniently an extension of the annular ring 34. However, the axial spacing between the remaining stages, as for example between e and f, is such that the actuator ring 32 and the free end of the levers 24 overlie the structure of the adjacent stage in order to provide the desired lever length. This overlapping is readily accommodated by simply offsetting the flange 47 (as is the case for the rings 32 of compressor stages b-g) which forms a part of the cooperating groove and tongue means employed in mounting each ring 32 for oscillatory movement.

FIG. 3 illustrates an alternate form of cooperating tongue and groove means for mounting actuator rings for oscillatory movement. Thus the ring 32 has an inwardly projecting flange 47 on which are formed projections or feet 50 that are received or journaled in a circumferential groove 52 formed in the compressor casing 10. FIG. 3 illustrates that with this form of tongue and groove means the ilange 47 may also be offset so that the actuating ring 32 overlies the structure employed for angularly adjusting the stators of the next adjacent stage.

In usual practice the stators of the several stages of an axial iiow compressor are simultaneously adjusted through the use of a common lever arm or like system. Such means in the present instance may be connected to the several actuator rings 32 or the rings 32 may be individually adjusted as desired with all the attended advantages of the present invention.

In either of the embodiments of FIG. 2 or 3 there is compound movement between the levers 24 and the actuator rings 32. This will best be understood from FIGS. 2 and 4 wherein it will be noted that the levers 24 swing arcuately along path w through plane x, while the actuator ring 32 and clevis pins 35D move through arcuate path y in plane z. The arcuate path w is accommodated as the clevis pins 30 oscillate in the journals on the ring 32 and project to a greater or lesser extent through the slots 28. The depth of the slots 28 is such that there can be relative movement between the levers 24 and the clevis pins 30 in an axial sense relative to the latter to accommodate the arcuate path y.

It will also be noted that the free ends of the levers 24 are rounded on a diameter equal to the distance between the opposed walls of the slots 23, so as to accommodate the relative rotational movement between the levers and the clevis pins without binding and yet maintaining a close control of the relative movement of the levers 24.

These latter advantages are also found in the modied embodiment of the invention illustrated in FIG. wherein the casing 58 pivotally receives a stud shaft 60 projecting from a stator 62. A lever 64 is secured to the stud shaft 60 by a nut 66. The stator 62 is illustrative of the several stators employed in a compressor stage in the same fashion as described in the previous embodiment. Each of the levers 64 of such a stage is received in a slot 68 disposed centrally and axially of a clevis pin 70 in the same fashion that levers 24 are received by clevis pins 30 in the previous embodiments.

The clevis pins 70 are pivotally mounted in an actuator ring 72 having a C-shaped cross section, the open end of which faces the adjacent stators so that the lever arms 64 may project therein. Again it is contemplated that the actuator ring may be compositely formed for convenience of assembly.

The clevis pins 70 are disposed radially of the casing 53 and are journaled in holes formed in the opposed arms of the ring 72. Integral concentric studs 74 project respectively from the inner ends of the pins 70 and are received by a groove 76 formed circumferentially of the casing 5S. The actuator ring 72 is thus mounted for oscillatory movement in a plane generally normal to the axis of the casing 58. The clevis pins 70 are formed with a flange 73 which is captured between the actuator ring 72 and the portion of the housing S8 defining the groove 76 to maintain the clevis pins 70 in assembled relation on the actuator ring 72.

It will be apparent that the levers 64 follow the same arcuate paths of movement in fixed planes as the levers 24 and that likewise the ring 72 follows an arcuate path in fixed plane, as did the ring 32. The action of the clevis pins 70 is therefore the same in accommodating the compound movements of these members to accurately impart a desired movement to the stators 62 upon oscillation of the ring 72. In this connection it will also be apparent that the free ends of the levers 64 are rounded in the same fashion as the free ends of the levers 24 so that there can be relative rotation between the pins 70 and levers 64 as previously described.

While the present invention has been described as it would be employed in an axial flow compressor, it will be apparent to those skilled in the art that the same concepts could also be used in adjusting the angular position of nozzle stators employed in turbines as well. This and other modifications of the invention will come within the scope of the invention which is to be derived from the appended claims.

Having thus described the invention, what is claimed as novel and desired to be secured by Letters Patent of thc United States is:

l. In an axial flow compressor or the like,

a generally cylindrical casing,

a plurality of stators disposed within said casing, each stator being pivotal about an axis radial of said casing,

said stators being arranged in a stage disposed generally in a plane normal to the axis of the casing,

each stator having a lever secured thereto, disposed exteriorly of said casing, and extending laterally from its pivotal axis,

an actuator ring mounted adjacent said stage of stators for oscillatory movement in a plane generally normal to the axis of the casing,

said actuator ring having a plurality of clevis pins mounted therein and pivotal about angularly spaced axes radial of the casing,

each of the clevis pins having a radially disposed elongated slot therein,

the levers of the stators being received in the slots of respective ones of the clevis pins such that compound relative movement can occur therebetween in the axial sense with respect to both the levers and the respective clevis pin,

whereby movement of the actuator ring will impart simultaneous pivotal movement to the stators.

2. In an axial flow compressor or the like,

a generally cylindrical casing,

a plurality of stators disposed within said casing, each stator being pivotal about an axis radial of said casing,

said stators being arranged in a stage disposed generally in a plane normal to the axis of the casing,

each stator having a lever secured thereto, disposed exteriorly of said casing, and extending laterally from its pivotal axis,

an actuator ring mounted adjacent each stage of stators, said actuator ring having a C-shaped cross section facing towards said stators with the free ends of said levers received therein,

said actuator ring having a plurality of holes disposed radially of said casing and extending through the opposed portions of its C-shaped cross section,

a plurality of clevis pins journaled at their opposite ends in the holes through the opposed portions of the actuator ring, each clevis pin embracing respectively one of said levers,

said casing having a circumferential groove underlying said actuator ring and said clevis pins having axial projections extending into said groove to provide for oscillatory movement of the actuator ring and resultant simultaneous movement of the stators.

3. In an axial flow compressor or the like,

a generally cylindrical casing,

a plurality of stators disposed within said casing, each stator being pivotal about an axis radial of said casing,

said stators being arranged in stages spaced along the length of the casing with the stators of each stage being disposed generally in a plane normal to the axis of the casing,

each stator having a generally flat lever secured thereto disposed exteriorly of said casing and extending laterally of its pivot axis,

an actuator ring mounted adjacent each stage of stators for oscillatory movement in a plane generally normal to the axis of the casing,

each actuator ring having a plurality of clevis pins mounted therein and pivotal about angularly spaced axes radial of the casing,

the free ends of the levers of the stators of each stage being embraced respectively by the clevis pins of the associated actuator ring,

said clevis pins having open ended slots with opposed parallel walls,

the side edges of said levers engaging the slot walls being rounded on a diameter equal to the spacing between said walls,

the actuator ring of at least one stage overlying the structure of an adjacent stator stage,

whereby movement of a given actuator ring will impart simultaneous pivotal movement to the stators of that stage.

4. In an axial flow compressor or the like,

a generally cylindrical casing,

a plurality of stators disposed within said casing, each stator being pivotal about an axis radial of said casing,

said stators being arranged in stages spaced along the length of the casing with the stators of each stage being disposed generally in a plane normal to the axis of the casing,

each stator having a stud shaft journaled in said casing and extending therethrough to provide for its pivotal movement,

a generally at lever secured to the outer end of each stud shaft, and extending laterally of the pivot axis,

an actuator ring adjacent each stage of stators,

cooperating groove and tongue means on the compressor and actuator rings providing for oscillatory movement of the actuator rings in a plane generally normal to the axis ofthe casing,

each actuator ring having a plurality of clevis pins mounted therein and pivotal about angularly spaced axes radial of the casing,

the free ends of the levers of the stators of each stage being embraced respectively by the clevis pins of the associated actuator ring,

said clevis pins having open ended slots with opposed parallel walls,

the side edges of said levers engaging the slot walls being rounded on a diameter equal to the spacing between said walls,

the actuator of at least oneV stage overlying the stud shafts of an adjacent stator stage, said actuator ring being in spaced concentric relation with said adjacent stud shafts,

said one actuator ring having an inwardly projecting ange axially otset towards said one stage and forming a part of said cooperating groove and tongue means,

whereby movement of a given actuator ring will impart simultaneous movement to the stators of a given stage.

5. A combination as in claim 4 wherein the actuator ring comprises three spaced, concentric circumferential flanges,

the inner two anges having bores therein providing journals for mounting the clevis pins,

said levers projecting between said inner anges and into the slots of said clevis pins,

said outer ange being relieved to permit insertion of said clevis pins into said journals,

said clevis pins each being grooved, and

snap rings received by said grooves and captured between said outer and middle flange to releasably secure the clevis pins on the actuator ring.

References Cited UNITED STATES PATENTS 2,305,311 12/1942 Jendrassik 253-78 2,842,305 7/1958 Eckenfels et al. 230-114 2,862,654 12/1958 Gardiner 230-l 14 2,924,375 2/1960 McKissock 230-114 2,933,234 4/1960 Neumann 230-114 2,936,108 5/1960 Balcom et al 230-114 3,079,128 2/1963 Burge 253-78 5 HENRY F. RADUAZO, Primm Examiner. 

1. IN AN AXIAL FLOW COMPRESSOR OR THE LIKE, A GENERALLY CYLINDRICAL CASING, A PLURALITY OF STATORS DISPOSED WITHIN SAID CASING, EACH STATOR BEING PIVOTAL ABOUT AN AXIS RADIAL OF SAID CASING, SAID STATORS BEING ARRANGED IN A STAGE DISPOSED GENERALLY IN A PLANE NORMAL TO THE AXIS OF THE CASING, EACH STATOR HAVING A LEVER SECURED THERETO, DISPOSED EXTERIORLY OF SAID CASING, AND EXTENDING LATERALLY FROM ITS PIVOTAL AXIS, AN ACTUATOR RING MOUNTED ADJACENT SAID STAGE OF STATORS FOR OSCIALLATORY MOVEMENT IN A PLANE GENERALLY NORMAL TO THE AXIS OF THE CASING, SAID ACTUATOR RING HAVING A PLURALITY OF CLEVIS PINS MOUNTED THEREIN AND PIVOTAL ABOUT ANGULARLY SPACED AXES RADIAL OF THE CASING, EACH OF THE CLEVIS PINS HAVING A RADIALLY DISPOSED ELONGATED SLOT THEREIN, THE LEVERS OF THE STATORS BEING RECEIVED IN THE SLOTS OF RESPECTIVE ONES OF THE CLEVIS PINS SUCH THAT COMPOUND RELATIVE MOVEMENT CAN OCCUR THEREBETWEEN IN THE AXIAL SENSE WITH RESPECT TO BOTH THE LEVERS AND THE RESPECTIVE CLEVIS PIN, WHEREBY MOVEMENT OF THE ACTUATOR RING WILL IMPART SIMULTANEOUS PIVOTAL MOVEMENT TO THE STATORS. 